Electrolytic Sodium Hydroxide and Chlorine and Related Commodities

Abstract

All electrolytic routes to sodium hydroxide and chlorine from sodium chloride brine have to contend with keeping the highly reactive products separated. Sodium and chlorine would react explosively together to return

$$ N{a^ + } + {e^ - } \to Na\,\left( {or\,NaOH + {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}{H_2}} \right) $$

((6.1))

$$ C{l^ - } - {e^ - } \to {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}C{l_2} $$

((6.2))

starting salt, and sodium hydroxide reacts vigrously with chlorine to give sodium chloride and sodium hypochlorite (Equations 6.3, 6.4), so that similar precautions are required with either sodium product. Two main procedures have

$$ 2Na + C{l_2} \to 2NaCl $$

((6.3))

$$ 2NaOH + C{l_2} \to NaCl + NaClO + {H_2}O $$

((6.4))

dominated the methods used to keep these products apart. One involves the separation of the electrochemical cell into two compartments by a porous vertical diaphragm which permits the needed passage of ions, but keeps the products separated.